Introduction: Randomized controlled trials (RCTs) investigating the efficacy of bone marrow cell (BMC) transplantation in patients with ischemic heart disease have provided discordant results. The true benefits of BMMNC therapy in these patients remain unclear.Hypothesis: We hypothesized that injection of BMCs in patients with ischemic heart disease would lead to an improvement in left ventricular (LV) structure and function.Methods: We performed a systemic review and meta-analysis of data from published RCTs that evaluated the efficacy of BMCs in patients with ischemic heart disease. Our literature search yielded 64 trials enrolling 3690 patients. We observed the effects of cell injection on LV ejection fraction (LVEF), LV end-systolic volume (LVESV), LV end-diastolic volume (LVEDV) and infarct scar size. BMCs were transplanted in patients with either acute myocardial infarction (AMI) or chronic ischemic heart disease (CIHD). Changes in outcomes of interest were analyzed using random-effects meta-analysis.Results: Transplantation of BMCs resulted in an improvement in LVEF as compared with placebo (3.09%; 95% confidence interval [CI]: 2.22 to 3.95; P<0.00001). Similarly, infarct scar size, expressed as a percentage of total LV, was reduced (-2.32%; 95% CI: -3.34 to -1.29; P<0.00001), as was LVESV (-6.77 ml; 95% CI: -9.22 to -4.33; P<0.00001). These results indicate superior remodeling following cell therapy. The reduction in LVEDV was not statistically significant. Improvement in LVEF was confirmed in a separate analysis of trials using cardiac MRI (1.78%; 95% CI: 0.67 to 2.88; P=0.002).Conclusions: Meta-analysis of data from RCTs indicate that BMC injection in patients with ischemic heart disease improves cardiac function and remodeling. Improvement in LVEF was confirmed in a separate analysis of RCTs using cardiac MRI.